I think a relationship is hard enough as the simple thing it is, without making a huge deal out of everything. Like the eggs cheese thing. Maybe he makes a big noise because he felt misunderstood, or intruded upon. If you cant get something that simple right, what hope is there for the rest of your relationship? I think hes saying he finds intimacy painful and or threatening. Its not him, its you, to coin a phrase. Hes not sure if youre the one.

Since you mention leaving home, i would recommend you read the book, Leaving Home by David Celani. Try to figure out how the two of you are trying to help each other. But that is probably a different thing than building a life together. He hasnt left home yet himself.